I often get this question and I am going to do my best to explain. The Navionics Updates card can be purchased through a Navionics registered dealer or online. the package looks like thisThe reason why a Navionics Updates card would be used is primarily if you have an existing Navionics card that is too old to update online through Navionics Chart Installer program, or if you have changed/upgraded GPS plotters that take a different format card (example: going from a GPS plotter that takes CF [Compact Flash] to a new unit that only takes MSD [Micro Secure Digital]).